[英]WPF Caliburn Micro CanExecute when property of binded object changes
我有問題,當我更改綁定屬性時,我的CanSave
方法不會被調用。
視圖包含一些Labels
和TextBoxes
...沒什么特別的......
TextBoxes綁定到對象的屬性。
<Label Target="{Binding ElementName=txtTitle}" Grid.Column="0" Grid.Row="0" Content="Titel" Foreground="White" />
<TextBox Name="txtTitle" Grid.Column="1" Grid.Row="0" Text="{Binding NewBook.Title}" />
<Label Target="{Binding ElementName=txtAuthor}" Grid.Column="0" Grid.Row="1" Content="Autor" Foreground="White" />
<TextBox Name="txtAuthor" Grid.Column="1" Grid.Row="1" Text="{Binding NewBook.Author}"/>
<Label Target="{Binding ElementName=txtIsbn}" Grid.Column="0" Grid.Row="2" Content="ISBN" Foreground="White" />
<TextBox Name="txtIsbn" Grid.Column="1" Grid.Row="2" Text="{Binding NewBook.Isbn}" />
<Label Target="{Binding ElementName=txtPrice}" Grid.Column="0" Grid.Row="3" Content="Preis" Foreground="White" />
<TextBox Name="txtPrice" Grid.Column="1" Grid.Row="3" Text="{Binding NewBook.Price}"/>
<Button Grid.Column="1" Grid.Row="4" Content="Speichern" Name="SaveBook" />
ViewModel定義了NewBook
屬性以及CanSaveBook
和SaveBook
方法
public Book NewBook
{
get { return this.newBook; }
set
{
this.newBook = value;
this.NotifyOfPropertyChange(() => this.NewBook);
this.NotifyOfPropertyChange(() => this.CanSaveBook);
}
}
public bool CanSaveBook
{
get
{
return !string.IsNullOrEmpty(this.NewBook.Title)
&& !string.IsNullOrEmpty(this.NewBook.Author)
&& !string.IsNullOrEmpty(this.NewBook.Isbn)
&& this.NewBook.Price != 0;
}
}
public void SaveBook()
{
try
{
this.xmlOperator.AddBook(ConfigurationManager.AppSettings.Get("BookXmlPath"), this.NewBook);
}
catch (Exception ex)
{
throw ex;
}
this.NewBook = new Book();
}
我想要的是, Save-Button
僅在CanSaveBook
返回true
時才可用,但是在用戶在文本框中輸入信息后檢查CanSaveBook
...我錯過了什么?
您遇到的問題是更改圖書的屬性不會在視圖模型上引發INotifyPropertyChange。 最簡單的方法是擺脫Book類並將Name,Price,ISBN屬性直接放在視圖模型中。 然后在setter中引發INotifyPropertyChange(並確保綁定是雙向的)。
然后,您可以在SaveBook方法中構建Book並使用它來調用您的服務。
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